An Investigation of Effect of Stand-Off Distance on the Material Removal Characteristics and Surface Generation in Fluid Jet Polishing

Abstract

Fluid jet polishing (FJP) is a versatile polishing process that has many advantages compared to other polishing processes. Stand-off distance (SOD) is one of the key parameters in fluid jet polishing. However, relatively little research work has been carried out to investigate its effect of SOD on material removal characteristics and surface generation in FJP. In this paper, a systematic investigation of the effect of SOD on the tool influence function and surface topography in FJP was conducted. Experiments were designed for FJP two kinds of materials corresponding to ductile and brittle materials. They are nickel copper (NiCu) alloy and BK7 optical glass, respectively. In this study, the SOD was varied from 2 to 35 mm. Analysis and discussions were made on its effect on the shape of TIF, material removal rate, and surface topography. It is interesting to note that the TIF shape becomes a Gaussian-like shape with large SOD both on NiCu and BK7, which provides a novel way to optimize the TIF in FJP. The variation of the material removal rate and surface roughness versus SOD on NiCu and BK7 were also determined from the experimental results. Moreover, the surface topography of NiCu and BK7 were characterized from the results measured from the white light interferometer and scan electron microscope. The outcome of the study provides a better understanding of the material removal characteristics and surface generation mechanism in FJP.

Investigation on fluid jet polishing of AISI H13 die steel using a single nozzle tool

“…The parametric study to determine the optimized polishing pressure, stand-off distance and polishing time to maximize the percentage change in surface roughness (% ΔR a ) in polishing AISI H13 die material is conducted using design of experiment (DOE) technique. These are the most critical parameters for transformation of W-shaped sectioned profile (central uncut material) to U-shaped sectional profile (uniform material removal) as reported by Wang et al 23 The central composite design (CCD) technique of response surface methodology (RSM) is used in the present work with three variables and five levels of each variable. The CCD method gives the central repeatability of process parameters to ensure the accuracy of the developed data/model.…”

“…The decrease in % ΔR a at higher stand-off distance is due to over polishing with the simultaneous increase in these two parameters. 23 The interaction of stand-off distance and polishing time is plotted in Figure 4. Figure 4(a) and (b) indicates that the maximum % ΔR a is observed at stand-off distance of 32 mm for the time period between 170 sec and 180 sec.…”

“…These are the most critical parameters for transformation of W-shaped sectioned profile (central uncut material) to U-shaped sectional profile (uniform material removal) as reported by Wang et al . 23 The central composite design (CCD) technique of response surface methodology (RSM) is used in the present work with three variables and five levels of each variable. The CCD method gives the central repeatability of process parameters to ensure the accuracy of the developed data/model.…”

“…The commonly used materials for the abrasive particle are silicon carbide, cerium oxide and aluminium oxide, out of which silicon carbide is having the best hardness of 9.5 (on Mohs scale). The values of the other fixed parameters used in the study, which are given in Supplementary Table 1, were selected based upon the literature, 14,23 and the initial experimental trials conducted on the set-up.…”

“…To maximize the surface finish obtained in FJP process, a better understanding about the interaction of jet pressure, stand-off distance and polishing time is required. In an FJP study on polishing of AISI H13 die steel, Wang et al 23 studied the effect of stand-off distance on the surface generation mechanism and material removal characteristics. It was found from the experimental results that the suitable range of stand-off distance to polish ductile and brittle material were 25-35 mm and 8 mm, respectively, with 1.1 mm nozzle diameter.…”